Method of and means for producing and augmenting electrical pulsations used in musical instruments



y 1, 1934- M. L. SEVERY 1 1,957,152

METHDD OF AND MEANS FOR PRODUCING AND AUGMENTING ELECTRICAL PULSATIONSUSED IN MUSICAL INSTRUMENTS Filed Aug. .19, 1932 6 Sheets-Sheet 1 Noun#13 8 Snventor 7 46777eZumZL5e1/e/ry B3 @L M. LJSEVERY 1,957,152

METHOD OF AND MEANS FOR PRODUCING AND AUGMENT ING ELECTRICAL PULSATIONSUSED IN MUSICAL INSTRUMENTS Filed Aug. 19, 1932 6 Sheets-Sheet 2 NOTEZNOTEfi-M NOT 20 22 1'5 1,

8 Snventor 6 B WWW/53m attorneys May 1, 1934. M s v 1,957,152

METHOD OF AND MEANS FOR PRODUCING AND AUGMENTING ELECTRICAL PULSATIONSUSED IN MUSICAL INSTRUMENTS Filed Aug. 19, 1932 6 Sheets-Sheet 3 4ZSnncntof mmlfiwery Gttorncgs May 1, 1934. L, SEVERY 1,957,152

' METHOD OF AND MEANS FOR PRODUCING AND AUGMENTING ELECTRICAL PULSATIONSUSED IN MUSICAL INSTRUMENTS Filed Aug. 19, 1932 S SheetS-Sheet 4 z 7- 7Mg 5 ml Y/A W12 /0 10 I I I ,I P I '0 EVA Q 0 J I I I I I I 6 Zmventor77ZeZumZZ5p/ue/ry May 1, 1934. M L SEVERY 1,957,152 METHOD OF AND MEANSFOH'PRODUCING AND AUGMENTING ELECTRICAL PULSATIONS USED IN MUSICALINSTRUMENTS Filed Aug. 19. 1932 s She'et s-Sheet 5 '1lI/IllIlIlIlII/IIIIIIIIIIIIIIIIIIll/I l'lll III II I] I [III Zhwentormay/L560;

Clttornegs May 1, 1934. M. L. SEVERY 1,957,152

METHOD OF AND MEANS FOR PRODUCING AND AUGMENTING ELECTRICAL PULSATIONSUSED IN-HUSICAL INSTRUMENTS Filed Aug. 19, 1932 6 Sheets-Sheet 6 3nnentor attorneys rPatented May 1, 1934 OFFICE METHOD OF AND MEANS FORPRODUCING AND AUGMENTING ELECTRICAL PUIJSA- TIONS USED IN MUSICALINSTRUMENTS Melvin L. Sever-y, Los Angeles, Calif., assignor to TheVoca'lsevro Company, Los Angeles, Calif.,, a corporationof DelawareApplication August 19, 1932, Serial No. 629,526

16 Claims.

This invention relates more particularly to a method of and means forproducing and augmenting the effect of electrical pulsationsused incertain types of electrical musical instruments in 5 which sonorousbodies or resonant masses are actuated by electromagnets energized by acurrent of electricity rendered periodically intermittent, undulatory orpulsatory.

An important object of the invention is the 10 attainment andmaintenance of a scale having a high degree of perfection, whether theinstrument is frequently used or is left idle forlong periods.

Another important object of the invention is the attainment'of animproved quality of tone and a vastly greater efilciency without anyincrease of the voltage or amperage of the intermittent, undulatoryorpulsatory current and, consequently, with a much increasedilife, volumefor volume of the tone, of the interrupting mechanism.

A further object of the invention is materially to lessen the cost ofoperating the instrument, very little current, relatively, beingnecessary for a large volume of tone.

A further object of the invention is the attainment of much greatersimplicity and cheapness of construction, very little additional wiringbeing necessary in the preferred form here disclosed.

Still another important object is-the attainment of a quicker, crisper,and more staccato attack of the tones, making possible the most rapidand delicate types of music with a technique as Versatile and rapid atleast, as that of the violin in the hands of a maestro.

Another and most important object of the invention is the efficient andcheap operation of sounders used in electrical musical instruments 40producing tones synthetically after the general method set forth in apatent granted to me October 29, 1929 and Numbered 1,733,630, so as topermit the several component parts of the various complex tones built upto be easily and simply synthesized.

A further object of the invention is a still greater increase ofefiiciency through the employment of sounders having a magnetic circuitwith but one air-gap in each case.

Other features of the invention pertain to the order, construction, andgrouping of parts so as to permit theattainment of any desired timbres,as for example, by the meam set forth in the patent just referred to,and the proper grading of musical utterances for, purposes or artisticexpression.

In U. S. Patent No. 814,878 issued to M. L. Severy and G. B. Sinclair,and dated March 13. 1906, the sonorous bodies were actuatedbyelectromagnets the energizing current of which was pulsated by beingpassed through revolving commutating mechanism traversing brushes. As aresult of this arrangement, the sounding of each tone produced at itsassociated brush a number of arcs per second equal to the number ofvibrations necessary to educe such tone, and as the current used wasrelatively large for loud tones, the arcs were very destructive of thecommutators. These soon roughened and the brushes had often to bechanged. Nor was this all, for as soon as the commutatorsbecame uneventhe tone suffered, due to imperfect contact and imperfect timingthereof. Various attempts were made to remedy these diificulties, but noway was found to prevent the rapid deterioration of the devices.

In my co-pending application, Serial No. 455,- 376, filed May 26, 1930,I describe a method of pulsating an electrical current in a manner torender negligible any arcing at the commutator. This is accomplished byhaving the magnetism rising in the associated core at the time that itsbrush breaks at the commutator. Iwo currents are used, one which issteadyjn the coil, and another which is interrupted at the commutator.The action of one of the currents thus tends to neutralize the other, sothat when both currents are on together the core is at its minimum ofmagnetism; or preferably, as ordinarily used, without magnetism at all.In this present case a current passing through the commutatingmechanism, and another passing around the same is also used, but theprinciple of this use is entirely distinct and for the most partdiametrically opposite. Here the polarities are alike and the current,which is steady about a speakingmagnet core during the pressure of itsassociated key, does not periodically decrease and augment the effect ofthe current passing through the commutator, but greatly augments theeffect of the commutator current at all times during the r of each ofthese coils vibration instantly whether or not the brush is on aconducting section, the response being both stronger and quicker, whilethe tone is also clearer and cleaner.

In the forms of this present case where two coils are used, it is to benoted that the coils are not wound one over the other, or even with twoparallel wires wound about the core in one operation, as this has beenfound unsatisfactory; neither are they wound to produce oppositepolarity. Where two coils are-used I prefer to wind them separately,each coil occupying its own separate position onthe core, and to connectthem with entirely independent circuits as shown, the

current passing through one coil not w through the other.

Condensers, which may vary in capacity with the periodicity of theinterruption, may be used across the break and across the magnet as welland, especially with the lower frequencies of interruption, thesecondensers will commonly be used simultaneously, thereby suppressingpractically all of the arc.

In the drawings:

Fig. 1 is a diagrammatic lay-out of the preferred form of my invention;

Fig. 2 is a diagrammatic lay-out of another form of my invention usingtwo coils with each speakin: ma net;

Fig. 3 is a similar view of a further form of my invention in whichpermanently magnetized cores are used, embodying also means for renewingthe magnetism of said cores at necessary intervals;

Figs. 4 and 5 are details of sounders and their magnets, showingmagnetic circuits with small single air-gaps;

Fig. 8 is a view of a permanently magnetized core carrying a soft ironcore surrounded by a coil of wire Fig. 7 is a diagrammatic lay-out ofparts of a device to decrease arcing;

- Figs. 8, 9 and 10 are detail views of various wiring plans for thecommutators;

Figs. 11, 12, 13 and are detail views of various types of brushes whichmay be used;

Fig. 15 is a diagrammatic view of a wiring plan including a brush of thetype shown in Fig. 12;

Fig. 16 is a fragmentary view of a commutator and brush of the typeshown in Fig. 12;

Fig. 17 is a diagrammatic view of an embodiment of my invention usingpermanent magnets of a type diflering from those employed in Fig. 3;

Fig. 18 is a side elevation of a sounder particularly adapted to the lowbass notes of the instrument;

Fig. 19 is a detail view of a damping mechanism for the sounders for thelow. bass notes of the instrument.

source of direct current. A wire 6 leadingtherefrom connects with wire 7which leads to brush 8 supplying commutators 9 through shaft 10, withpositive current. The commutators 9 are under-v so that, as thecommutators revolve, a pulsating,

current is delivered through the brushes 11 and wires 12 to the coils 13wound upon soft iron cores 14, of the speaking magnets, The otherterminal iawiredto a second contact 15 of a relav'here as m aboveofthese'relaysisprovided withtenpairsoi' coacting contacts, and some ofthese contacts are, as shown, connected with portions of thepartialmixing system seen above them. As the purpose of this wiring isfully set forth in my copending N application, Serial No. 472,969, filedAugust 4, 1930, (now Patent No. 1,899,884 dated February 28, 1933, andas it is necessary to show it here only to indicate one feature of thepresent invention, it will be described only as it applies to this 1present application.

Tracing the circuit energizing the coils 13 it will be seen thatpositive current flows via wire 6 to the wire 7 thence to brush 8, shaft10, commutators 9, brushes 11 and wires 12 to one pole of eachmagnet-coil 13, thus serving said coil with pulsating current of aperiodicity determined by the associated commutator 9. The same pole ofthese coils 13 is also served with unpulsated'current during thesounding of associated sounders, 9B the circuit being as follows: Fromwires by wires l8to 17 andwires12tothealready mentioned poles of thespeaking-magnets, and from the other poles of said magnets by wires 18to the second contacts 15 of-the relay system already referred to. Fromthese contacts 15 both the pulsated and the unpulsated currents passtogether through the relay system atically represented by the contacts15, 15-, 15 15, and so on; through the partial-mixing system Idiagrammatically represented by the switches 4,

4*, 4', 4, 4", etc., by means of the wires 3;

h the expression-control system represented ticaliy by the switches 2,2, 2,

2, etc., by means of the wires 1; and by the 11. wire 86 to the tremolomechanism diagrammati- (ally represented at 87, said currents returningto the negative side of generator 5 by means of the wire 88.

In some applications of my invention it is un- 11 necessary to pass boththe pulsatory and the unpulsated currents together through the differentmechanisms, since the two currents may be kept essentially independentof each other. In the embodiment shown in Fig. 1, however, the tone 1aqualities are synthetically built up, and it is desirable that thepressure of a single key of the manual shall often cause a plurality ofsounders to speak, one for each partial of the timbre desired. It willtherefore be obvious that, since a given key is normally associated witha given relay which it operates, this relay must be able to elicit allthe tones for the partials required for the predetermined tone quality.

This is made plain in Fig. 1,. where the pair 190 of contacts 15 of theleft-hand relay represent the prime or first partial of the toneassociated a t with that relay, this tone being normally educedReferring to Fig. 1, the numeral 5 indicates a by the pressure of theiirst note of the key-manual, which in the case of my instruments is the138 note C of 32.33 vibrations per second. The next co-acting-pair ofcontacts, 15". above that already mentioned is associated with thesecond partial of this note 0 of 33.33 vibrations, and the pair 15"above that with the third partial of 140 the same note, and so on inorder for the rest of the partials available. The lower pair of contactsof eachrela'y a, used fora graded suboctave and, as the note #1 hereindicated has no such sub-octave, it cannot bev wired to anything below.It will be noted that the right-hand contact ofeach pair in the relayassociated with note #1 is wired to the similar contact of the relayassociated withnote #2, as set forth in my aforesaid companionapplication, Serial No. 472,989.

results. Where current consumption is of no moment, even more coulddoubtless be used, the

limit being that point so near saturation that the I relatively weakpulsating current is unable to produce a sufllcient change in themagnetic flux to ciated key, through the agency of current which doesnot pass the commutator brushes 11. Condensers 25 across the poles ofthese coils 24 serve to absorb the are when the current is cut out ofthem upon the release of their associated keys.

- The form shown in Fig. 2 is slightly more eillcient arrangement setforth in Fig. 1

for the .samemmount of current than the simpler embodiment shown in Fig.l by reason of the fact that the resistance" 17, Fig. 1, merely holdsdown the current without being in itself productive of any magnetizationof the core 14, while the coils 24 hold down the current by resistancewhich is productive of magnetism. In actual practice it has been foundthat it takes about one-fifth more current to produce the same volume oftone,

other things being equal, where the resistances 17 are used instead ofthecoils 24. Over against this is the increased cost of the coils, andas the current consumption is very small anyway, the is preferred forall ordinary purposes. I

It is to be understood that the operative systemor circuit, so-called,is not shown in these figures. as it would needlessly complicate thedrawings, It will suffice if it be simply understood that whena key ofthe manual is played an associated magnet is actuated, with the resultthat the ten pairs of co acting contacts such as 15, 15, 15', 15, etc.of its associated relay, are brought into touch, thus providing a pathor paths through the rest of the system by which the current returns tothe other side of said source 5.

' In the partial switches diagrammatically shown in Figs. 1 and 2 itwill be noted that the resistances 4 are omitted from all the switches4, since said switches 4 are merely used as cut-out switches to preventpartials sounding at all when they are not wanted in tonal combinations;These partial switches and the switches 2, 2, etc. of theexpression-control system above them are diagrammatic representations,in part, of what I term my permuting system", which is'clearly set forthin my application Serial No. 650,179, filed January 4,1933.

In Fig. 3 a variant form of theconstruction of Fig. 1 is shown, whichmay be used in certain types of instruments not requiring the maximumpower possible to attain, or the greatest possible evenness of scale. Inthis case the core 14' is a permanently magnetized core of steelcarrying a coil 13, the connections to the commutating mechanism being,in principle, similar to those of Figs. 1 and 2. The magnetism of thecores 14', whether it be produced as in Figs. 1 or 2, or by theso-called permanent magnetism of Fig. 3. has a very great effect uponthe volume I of tone. and this effect, of course. other things beingequal and up to that certain point 'of saturation already adverted to,will vary .as the magnetism produced by either of the two last-namedagencies varies. This variation, however, will not be insimpleproportion, for the pull between a magnet and its number of magneticlines that come into action. It is by taking advantage of thisgeometrical proportion that I secure the remarkable results madepossible by this invention. It must, howmagnetism, be not thoroughlydependable as to strength, both as between different parts of the scaleat one time or at diflerent times, and as between the whole scale atdifferent times. Not

only must the scale be even in its parts, but the augmenting magneticfactor, of either type. must not be strong today and weak a,month orthree months hence, not even if every tone-augmenting magnetic factor inthe instrument vary in like proportion, for, as will readily be seen,the resistances used in the partial-mixing and expression-controlsystems are definitely wired into the instrument, and cannot be adjustedat will to compensate tfor fortuitous variations of volume.

It is of course well known that permanent magnets lose a portion oftheir magnetism after magnetization, and where they are not providedwith a keeper securing a magnetically closed nently magnetized cores areused and the cost is not prohibitive for the type of instrument, to

provide a means for quickly raising and evening up the magneticintensities of these permanently magnetized cores. A convenientway ofdoing this manually is shown in Fig. 3, but it is to be understood thatit may be done automatically at fixedintervals, as for example, eachtime an instrument is turned on, a strong current may be momentarily letinto all the coils 13' surrounding the permanently magnetized cores 14'.This method is, of course, within the scope of my invention as well asthemethod of accomplishing the same result manually which is here shown.

It is to be remembered that it isalways desirable to pass as littlecurrent as possible through the commutators, for reasons which will beapparent, and it is the very purpose of this invention to decreaseimmensely the amount of current.

which has to be handled by commutators and brushes in the production ofa satisfying degree of volume, so that, while the tendency of theinterrupted current would be to magnetize slightly the cores of hardsteel around which it passes, it is far too weak to be of any greatassistance in keeping the cores ,up to strength after they are oncemagnetized. Since some sections of the instrument are inevitably playedfar more than other sections, it, is imperative that the magnetism ofthe cores shall be sufficiently strong not to be increased by thepassage of this weak pulsating current, lest it should be impossible tomaintain an evenness of scale.

It is for thesereasons that I provide the rearmature is proportional tothe square of the mechanism shown in 3, where It will now be seen, inview of what has just been said, that it is necessary in this preferredform of synthetic tone production shown at Fig. '1 to pass both thepulsated and the unpulsated currents through the relay system, .thepartialmixing system, the expression-control system, and the tremolosystem, despite the fact that this additional current will require allresistances throughout the various systems to be of somewhat largercapacity. Tracing the circuit with respect to a fundamental and a singlehigher ,wire 18 to coil 13 of the associated speakingmagnet, and thencefrom the other terminal of said coil 13 by wire 12, brush l1 andcommutator 9 back to generator 5 by wire 6, thus completing thepulsating circuit. Current also passes from the right-hand pole of theassociated speakingmagnet by wire 12 to resistance 17 and wire 16 backto generator 5 by wire 6, thus completing the unpulsated circuit, itbeing noted that this unpulsated current passes around and not throughthe commutator. While this is occurring, current is crossing from theright-hand to the left-hand contact 15 whence it passes by wire 19 tothe left-hand contact 15 of the second pair of co-acting contacts of therelay normally associated with note #20, whichnote is a musical twelfthabove note #1 and is, therefore, in the relation of a third partialthereto. From this last-mentioned left-hand contact 15 current passes,without the closing of the associated relay, to coil 13 of the speakingmagnet associated with note #20; thence through commutator 9 in onecase, and around it and through the resistance 17 in the other, passingback through wire 6 to the positive pole of generator 5. Condensers,which will vary greatly in capacity according to the frequency of thepulsations of thecommutators 9, are distributed to attain the bestresults possible. For some pitches, a con denser 20 connected to brush11 on one side and by the wire 21 to the wire 6 on the other side, isplaced across the break, while in other cases it is found to work quiteas well placed across the coil as shown at 22, a wire 23 connecting thecondenser with wire 12 and thereby with the other connections leading tothe speaking-magnet, the wire 24 joining said condenser to the otherpole of said magnet. In some cases I find that condensers placed in bothof these positions give the best results of all by suppressingpractically all the are. In Fig. 1 it will be noted that the resistances1'? are in shunt with the condensers 20.

The placement of the resistances 1'? is illustrated in detail in Figs.8, 9 and 10, but in each instance the co-acting contacts 80, 81 areoperated directly by pressure of the keys of the manual, and not throughthe relay system of Figs. 1 and 2. Condensers have been omitted in Figs.Q and 10, but may be used as described in connection with any of theother figures, for the purpose of decreasing the arcing at thecominutators. The resistances 1'7 may be replaced by, or used inconjunction with a resistance placed in the brush member itself asshowif in ,Fig. 14, and as will be more fully described later. Aresistance so placed and of contacting dimensiohs sufficient to bridgethe gaps-between teeth of the commutator, will give a continuous currentafter the manner of the resistance 17, but it is to be noted that insuch practice all the current which passes the high resistance member,as well as the pulsated current which traverses the low resistance partof the brush, passes through the commutator. Furthermore, should thebrush contact vary in the rotation of the commutator, this highresistance member would be materially affected thereby, whereas jtheresistance 1'! would not. Balanced against these considerations,however, are the facts that the brushes carrying the relatively thick,high resistances prevent the tendency of the metallic part of the brushto dig into and so wear the commutator. Moreover, the high resistancemember may be provided with a lubricant, as graphite, which will stillfurther assist in the protection of the commutator. Indeed, so importantare these last-named factors that even where the resistance member 17 isused, it may be desirable to use also the broadened brush member ormembers with or without the lubricating factor, even when theirresistance is so high as to be sensibly infinite and their passage ofcurrent negligible.

The placing of very high resistances in parallel with condensers is wellknown and is said to hage originated with von Helmholtz, who used itsolely for the purpose of aiding in the suppression of arcing. While Ihave tried this method many times, it has not produced any outstandingdiminution of arc, although it apparently did change the color of thearc and so, perhaps, lower its burning proclivities. Very highresistances were employed according to well-known practice, and thesewere usually made non-inductive. It has also been proposed to use veryhigh resistances which must always be non-inductive, that is, notcoiled,- placed across that part of the circuit where the gap is to bemade at break, so that the arc will not so readily leap the air-gap butwill pass through this high non-inductive resistance. It has been statedthat a coiled wire is of no use, as the discharge refuses to go aroundits convolutions, and a very thin platinum wire has been suggested, oreven a streak of a plumbago pencil on a roughened surface.- Theresistance to be used should, according to various formulas proposed, befrom forty to sixty times that of the magnet coil. Shunting with a.condenser either across the break or across the coil is common, though Iam not aware that condensers have heretofore been used in both places atonce. The point to be borne in mind in this present case is that thisapplication is not directed to suppression of the arc, but to increaseof the magnetic efficiency without altering the arc in any sensible Way.Therefore, the resistance 17 of Fig. 1 need not necessarily benon-inductive whether it be placed across the break as in said or acrossthe magnet coil as in Fig. 10, for in this invention its use is a steadyone throughout each pressure of the associated key. In this presentinvention the value of the resistance i7 is so lowered that it providesa strong, steady magnetic field in which the pulsating current passingthe commutator acts, thereby greatly enhancing and improving the tone. Ifind in the preferred form with a current of thirty volts, that a steadyflow of from a fifth to a quarter ofan ampere about the coils 13 givesmost excellent a manual or automatic stop 26, or similar means, is shownfor closing a switch'again'st the action of a spring 2'1, and causing abar 28 to bridge co-acting contacts 29, 29', thus energizing magnets 30,31 and 32, the path of the current being as follows: From the plus poleof the generator 5 by wire 33 to contact member 29; thence by thebridging bar 28 to contact member 29'; thence by wires 34 and 35 to wire36; thence to one pole of each of the magnets 30, 31 and from the otherpoles of each of said magnets by wire 37 to wire 38; and thence by wire6 back to the minus pole of generator 5, thus energizing magnets 30, 31.The wire 34 also runs to one pole of magnet 32, the other pole of saidmagnet being joined, through a wire 6, with the minus side of generator5 thusenergizingmagnet 32 so that,-whenfstop 26 is pressed to the right,magnets 30, 31 and 32 are all energized. The functions performed by themagnets 30, 31 and 32, when energized, are as follows:

The magnets 30 and 31 attract and pull down arms 39 to which areattached bridging bars 40, 40 adapted to contact co-acting members 41,41, 42 and 43, members 42 and 43 each being in number equal to all thespeaking-magnets of the instrument whose cores are to be magnetized bythis device. The bridging bars 40, 40 are broken away to indicate thatthey bridge many more contacts than are shown, only the principle ofoperation being here indicated. It will be noted that wires 44 join onepole of all the speaking-magnets to contacts 42 bridged by bar 40, whileall the other poles of said speakingmagnets are joined by wires 45through resistances 46 to contacts 43 coacting with the bridging bar40'. The contact 41 is joined .to a contact member 48 which co-acts witha member 49 in circuit with a wire 6 leading to the negative pole of the.generator. When magnets i 30, 31 and 32 are energized, armature 50 isdrawn upwardly against the action of spring 51, thereby closing contact49 against contact 48 and separating contact 49 from contact 52, thuscutting off the negative pole of the generator from wire '7, brush 8 andcommutator shaft 10. At the same time the circuits in all the coils 13of the speaking-magnets are completed without any passage of the currentthrough the commutating mechanism, and with the full voltage of theunpulsated generator current resisted only by the resistances 46 and theresistances of the coils 13 wired in multiple, so that, with a generatedcurrent of thirty volts, with resistances 46 at fifty ohms each andcoils 13' at ten ohms each, each coil 13 would be traversed by a halfampere of current during the pressure of stop 26. Immediately upon therelease of stop 26, however, magnets 3O, 31 and 32 are all de-energized.member 49 contacts with member 52, leaving member 48; bridging bars 40,40 move upwardly; and the whole system is ready for tone production bythe energization of the speakingmagnets by the pulsated current from thecommutators 9 assisted by the magnetization in the cores 14.

The system shown in Fig. 3 is not without some advantages over thatshown in Fig. 2 as, for example, dispensing with one,coil on eachspeaking-magnet core, but this is more than overbalanoed by the factthat the results are much inferior with permanent than withelectromagnetic magnetization. for it is not feasible to magnetizepermanently to the same degree of strength that can be attained by theelectro-.

magnetic method, to saynothing of the difliculty of securing constantand constantly persisting magnetization. These reasons, without goinginto others, are sufiicient to explain why I prefer, whenever possible,to use the construction shown in Fig. 1. In cheap instruments where theremagnetizing wiring may be omitted and.

the resulting unevenness of scale tolerated, the method of usingpermanent cores becomes somewhat more attractive from the cost aspect ofthe matter. I

Fig. 4 shows two of a set of speaking units of fairly high pitch,illustrating my method of securing a magnetic circuit with only one verysmall air-gap. In this figure reeds 53 which may be round if desired,and are so shown, are

fastened to a substantial iron casting 54, the

outer ends-of said reeds coming over and very near to the heads ofmagnet cores 14 which are adjusted up or down, for voicing, by nuts 55upon the threadedportion of"cores"l4r 'To'the'ends of reeds 53 arefastened upright pins 56, adapted to carry cup-like resonators 5'7, 5'7,preferably of very light material as, for example, pasteboard, pyralin,or the like. 5'7 indicates a diaphragm-like bottom secured within thetube 57, the tube 5"! being shown with its bottom removed and replacedby a plunger-like member 57. The magnetic circuit is very short and thestructure very eificient. The magnetic circuit is from the head of core14 across the slight air-gap to the reed-53 of magnetizable metal,through the upright portion of casting 54 to the base thereof, andthence by nuts 55 and the threaded portion of core 14, completing thecircuit. The already familiar coils 13 and 24 and their wiring need nofurther explanation except to state that, under the system shown in Fig.1, the coils 24 would be dispensed with.

Fig. 5 shows a type of sounder with a single air-gap magnetic circuit,adapted to tones .of lower pitch. This sounder is preferably used in ahorizontal position, but may of course be placed in any desiredposition. Here the resonator 58,

which may be a wooden pipe of square cross section, has a plunger-likemember 59'formed so as to move as .a whole under the action of the baror reed 60, to the center of which it is firmly also preferably of ironor steel, and may for convenience and compactness be bent up at anangle, as shown at 64. Springs 650i a thin magnetizable sheet metal aresecured by rivets or otherwise, to

the bent reed 60 at the lower ends of its upright sections, so that amagnetic metallic circuit is here secured. The other ends of springs 65are fastened to the member 66, which are also of magnetizable metal, andare secured to the steel or iron members 6'7 holding the resonator 58.The magnet core 14 is adjusted to and from the reed 60, for purposes ofvoicing, by lowering or raising the member 68 through the agency ofscrews 69 and nuts '70 co-acting therewith. The upwardly bent ends ofreed 60 may be weighted or shortened if the reed benot near enough tothe natural pitch of the resonator with which it co-operates. Theflexible hanging of reed 60 by the springs 65 renders the reedexceedingly magnetic circuit, as will be seen by a glance at thedrawings. The forward end of core 14 is 6 close to reed 60, which is ofmagnetic metal, and

- usually employed, are here shown, each of said this reed is securedbythe springs of steel or iron, to the iron or steel members 66 whichcarry the magnetizable screws 69 upon which is fastened the iron orsteelmember 68 to which is secured the member 63 of magnetizable materialwhich leads the magnetism back to the rear end of the core 14, offeringa complete metallic magnetic circuit save only for the single slightairgap between the core-head and the adjacent reedarmature 60; In thisway the eiiiciency of these practically closed magnetic circuits is madeto increase still further'the emciency of the system herein set forth.In this case also it is to be understood that if the system of Fig. 1 beadopted, coil 24 will be dispensed with. In Fig. 6 I show a permanentlymagnetized core 74 into which is fastened a soft-iron core 75 aroundwhichis placed a coil 76. This construction could be used'for speakingmagnets as a variant of the system shownin Fig. 3, but it would be moreexpensive and even less efllcient,

and it offers no good way of keeping the perma nent magnetism up to afairly constant and efficient strength.

It is to be borne in mind that the current I use is a uni-directionaland not an alternating current, and that I prefer to have the samepolarity of current in both the coils 13 and 24, where both are used, asby far the best results have been obtained in this way.

There are other ways of increasing the intensity of the field in whichthe speaking-magnets act without increasing the current passing throughthe commutators, and I hold any of these to be within the province of myinvention, though I have found none of them, all things considered, tobe as good as the preferred form shown in Fig. 1.

Fig. 7 illustrates a methoddevised some years ago to decrease the arcingat the commutators. Two of the groups of rotors or commutators 9 groupsbeing mounted. on a shaft 10, and each commutator 9 being traversed by abrush 11 as heretofore explained, the brush 8 in contact with said shaftbeingalso shown. Each brush 11 is.

connected'with a non-inductive resistance 1'7, in this case of 200 ohms,the other'ends' of all said resistances being joined to a bus-wire '71connecting all the resistances 17 together throughout the instrument.From wire '71 a wire 72 leads to a non-inductive resistance '73 of 4,000ohms, and from thence a wire 77 leads to the negative pole of the sourceof current. It will be seen, therefore, that when a key is pressed andthe associated brush arcs, there is a 4200' ohm noninductive resistanceacross the break. This system has been used with a direct current ofthirty volts, and apparently makes the are somewhat less destructive andof somewhat diiferent' color. when the resistance 73 is omitted, theaggregate current consumption of the resistances 17 in parallel, is toolarge. The employment of resistances aggregating 4,200 ohms permits onlyone one-hundred fortieth of an ampere of current to pass, and this isstill further out down by the resistance of the speaking-magnet.

In Fig. 10 a resistance 17 is shown in a location different from that ofmy preferred construction. It has been observed that this resistance, ifof the same value as that md for the prererred construction of Fig. 1.will cause a noticeable increase in tone when the coil 13 is taking froma fifth to a quarter of an ampere of current, but the arcwillalsobeincreased,forallthecurrentused is made to pass the commutator,which fact is much against the system, this invention be concernedprimarily with increase of tone rather than primarily with decrease ofarc. a

In Figs. 11 to 14 variant forms of brushes to be used with thecommutators are shown, the numeral 11 in each instance indicating aconducting strip which is commonly of metal and may well be silver,placed upon the thicker members 11- whose function is to prevent the.relatively thin metallic strips 11 having a digging action and thusexcessively wearing the commutators. The members 11 may be impregnatedwith a lubricant, as graphite, or formed with a lubricant as aningredient, as indicated at 11", Fig. 14, but said members are, asshown, of so high a resistance to current that at ordinary voltages theymay be practically considered as insulators. In the forms shown in Figs.12 and 13 it will be noted that the members 11 have a still furtheradvantage, in that they wipe out or quench immediately any are whichmight tend to form at the leaving edge of the brush. As seen in-Fig. 14the high resistance substance 11, as for example, carbon or compressedgraphite, is of a thickness sufficient to bridge the conducting teeth ofits associated commutator ring, and has a contact resistance sufficientto give the requisite amount of steady current during the pressure ofits associated key, thereby serving as a substitute for the resistance17 of my preferred form shown in Fig. 1. The portion 11 as will beobvious, serves also as a "wiper" to extinguish the are, if any, whichmight be formed at the leaving edge of the low resistance member 11 ofthe brush. Where desirable another member 11 may be placed below the lowresistance member of the brush shown in Fig. 14, after the manner shownin Fig. 13.

In Fig. 15 is shown a commutator ring 9 traversed by a brush composed ofmembers 11, 11, though it is to be understood that any of the brushconstructions just described could be used in place of the specific oneshown. The usual circuit, omitting all the unessential parts, is showndiagrammatically. This comprises the magnet coil 13 and core 14, theco-acting members 83, 84 closed by pressure of a key of the manual, thesource of current 5, and the connection 6 between thesame and thecommutator 9. When the contacts 83, 84'are closed through pressure ofthe associated key, the circuit is completed from the brush 11 andmagnet coil 13 to the minus pole of generator 5, and from the other polethereof to commutator 9 and the bearing portion of said brush.

In Fig. 16 a brush comprisingthe high resistance portion 11" and lowresistance portion 11, is shown, but said brush may, wherever desirable,be of the type of Fig. 14. In this figure it will be seen that if thethicker member 11 0! the brush have, say, a surface resistance of 150ohms when of the type of member 11 of Fig. 14, such is its thicknesswhen added to that of the member 11, that it will bridge thenon-conducting spaces 85 between the commutator teeth, so that duringthe L monly used, to wit, thirty volts.

' move damper 103 from the vibrating member,

In Fig. 17 a laminated permanent magnet 89 isshown, provided at itsupper end with a soft iron core 90 about which is a helix 91, one end orwhich is connected to a brush 11 bearing upon a commutator 9 of the typeshown in Figs. 1, 2 and 3. A sound-board 92, a rib 93 thereof, and abridge 94 to which an ampliiler 95 is secured,

are also illustrated in this figure, the amplifier.

95 carrying an armature 96, co-acting with core 90. A manual key 97 forcompleting the circuit, and the expression-control mechanism 98, 99 anda 100 are diagrammatically illustrated. When key 97 is open the core 90is magnetized and the armature 96 attracted, the commutator 9 of course1 being driven at correct speed. When key 97 is closed, current willtraverse coil 91 at each passage of a conducting section or commutator 9beneath brush 11, thus morewr less neutralizing "the effect of magnet 89upon core 90, and through 0 it, upon armature 96, which-will then movesome-- what away from the pole or core 90. The degree of neutralizationwill depend upon the relation of contacts 98, 99, thatis, upon theamount of resistance inserted in the circuit of which helix 91 is apart. This method may be employed with advantage in instruments notrequiring the maximum power possible to attain or great evenness ofscale.

' In the preferred form of my invention shown in Fig. 1 the resistances17 need not necessarily be non-inductive, and especially in the case ofthe lower notes of an instrument should not only be wound inductively,but should have a core of soft iron. If thisprocedure is not followedthe results, especially on the notes of low periodicities, are muchimpaired. Where this choking effect of the iron core is omitted, thepulsating part of the current seems to put a'surge into the supposedlysteady current, with the result that the are at the break of thepulsating system is greatly enhanced and the speech of the soundersimpaired, particularly in the low sections of the instrument.Furthermore, as seen in Fig. 18 where a large horizontal sounder of thepipe type is shown, the moving parts are of considerable mass and, itthese are to be started promptly and damped promptly, special means mustbe used. In said figure the construction of the resonator is similar tothat shown in Fig. 5,

5c and the same reference numerals are used to indicate similar parts.In Fig. 18, however, the coil 17 serves "to supply immediateuninterrupted current to the magnet 13 the instant the corresponding keyof the manual is pressed, said coil serving, just as does the resistance17 of Fig- 1, to start the tone promptly. As the coil 17 is shown withits core 101 not only serving to provide the choking action Kah'eadyadverted :to, butalso to attract rocker arm 102 and thus it' will beseen that it'also gives an immediate damping otthe tone and'cuts out allundesirable .fhold-over". Arm 102 is carried by a standard 104 suitablysecured to pipe 58, a spring 105 serving to keep damper 103 on until thenote is played, when the choke coil 17 not only performs its function"ofincreasing the'tone and holding down the are, but also undampsvibrating memo ber. and permits it to sound. when its cor responding keyis released, coil 17' as quickly becomes de-en'ergized and permitspressure of damper 103 against the yibratlng member 60, thus cutting thetone oi! sharp y. and with no 7 disagreeable hold-over". The wires 16'arm 118.

12 from the coil 17', Fig. 18, connect respectively with wires 16 and 12of Fig. 1.

It will be noted that the legs of vibrating member 60 are turned so asto roject along the pipe lfor purposes of economy 0 space and protectionagainst being hit.

I have found the choking action of coil 17' with its iron core necessaryif increased loudness of speech is to be attained without in anysensible way altering the pulsating circuit per se, or increasing itsarc, and that this is increasing- 1y true in degree as the lower end ofthe scale is approached. As the frequencies of interruption increase,the iron core becomes less necessary, and as the masses moved are alsosmaller, the attack is sufllciently quick and self-damping becomessuilicient. Thus it will commonly not be necessary to carry the chokingaction of the resistance which permits a steady current, throughout theentire scale, though there may be cases where it will be desirable so todo.

In Fig. 19 another means of damping the tones of the low bass octaves ofthe instrument is shown. A portion of a resonator 58' has associatedwith it a magnet 106 which acts as a relay, and serves to close acircuit which may be always of constant pressure, said circuit operatingto close the aperture 108 in resonator 58, said aperture beingpreferably placed at a point not a natural partial of the tone intendedand given by the full pipe. The magnet 109 in circuit with magnet 106perform the arduous work of the real damping. 110,. 111 indicateconnections from magnet 106 to the wires 16 and 12 of Fig. 1 or similarwires. said magnet being here employed instead of the resistances 17 ofFig. 1. These dampers will probably be required for only the lower andlarger pipes, and will probably be used on the lowest two octaves andpossibly only on the very lowestoctave. In some cases it might not benecessary to employ any damping, but where the maximum clearness ofspeech is required, it is preferable to damp the lower notes in thefiner types of instrument.

Aperture 108 is normally open, rocker arm 112 carrying the pad or damper114 being raised through the agency of spring 113, but is closed by saiddamper while the tone is being produced, the rocker arm lifting the pador damperthe instant the key is released. When the damper is removed andthe apert V uncovered, the pipe no longer suits the pitc of reed 60, andthe resonance and consequently the tone, immediately cease. The magnet109 is in circuit with a source of power 115 which is constant or notaltered when the instrument is played. 116, 117 indicate co-actingcontacts carried respectively by rocker arm 118 and by the non-conductin.iiber head 106 ot magnet 106, the wire 119 from "magnet 109being19nnected to a stud or pm 119 passing througlri aaid head 106 These pinsor studs are of conducting material, the current passing from one pin tothe other through the It is to be understood, therefore,-that for thelower octaves ot the instrument, one or more, it is preferred to use th,separate coil and core 17 illustrated in Fig. 18 while most or all ofthe other octaves of the instrument it is pre- 'ferred to use the doublecoil magnets illustrated inFig. 2.,

Musical instruments of the type here disclosed are usually actuated by auni-directional current of about thirty volts, which in the case of thepresent invention renders it necessary to use .relatively low resistancefor any coils intended to produce a suitably strong, steadymagnetization of cores for the purposes herein set forth and explained.When, therefore. in the specification or claims the expression "strong"or relatively strong" is used, itis to be understood as meanin a veryappreciable part of the total possible magnetization of a core for, ashas been pointed out herein, it is desirable to have the steadymagnetization strong, and the tone may be increased with each incrementof such strength up to, but not passing, that degree of saturation whichwill still enable the fluctuant current to make itself sharply felt witheach increment 01' its current.

I claim:--

1. The herein described method or increasing the action of aunidirectional pulsated current traversing a coil around a core ofmagnetizable metal, which consists in causing an armature associatedwith said core to act in a relatively strong magnetic field which, ofitself and apart from the field produced by the fluctuant current, issensibly steady during the action or said unidirectional pulsatedcurrent, both said currents being of the same polarity.

2. The herein described method of rhythmically vibrating a sounder of amusical instrument, which consists in rhythmically pulsating aunidirectionalcurrent; passing said current about a core to which aportion oi said sounder acts as an armature; and causing said core to berendered strongly magnetic apart from, and with the same polarity asthat produced by said pulsated current, the increase in the magnetismproduced by said unpulsated current being steady during the action ofsaid unpulsated current.

3. The herein described method of rhythmically vibrating a sounder oi amusical instrument, which consists in providing a unidirectionalrhythmically pulsated electrical current rendered operative at will;operating said sounder by said rhythmically pulsated electrical current;and creating a strong magnetic field during the action of said pulsatedcurrent, thereby greatly increasing the effect of said last-namedcurrent,both said currents being of the same polarity.

4. The herein described method oi rhythmically electromagneticallyvibrating a sounder by a rhythmically pulsated, unidirectional current,which consists in delivering said current at will to an electromagnetoperating said sounder; and creating and maintaining throughout theentire action of the pulsated current a strong magnetic field which, 01itself and apart from the field produced by the fluctuant current issensibly steady, and upon which steady field the fiuctuant field is,superposed, thereby greatly enhancing the eilect oi the fluctuantcurrent, both said currents being of the same polarity.

5. The herein describedmethod oi electromagnetically producingrhythmically timed movements in a sounder, serving in part as anarmature to an actuating magnet, said method consisting in supplying theactuating magnet, during the operation of said sounder, with two kindsof magnetization of like polarity, one strong and sensibly continuousand the other pulsatory in accordance with the rhythmical movementdesired.

6. The herein described method of producing and augmenting the timed,rhythmical movements of a sounder or a musical instrument, whichconsists in rhythmically varying the strength of a relatively strongunpulsating magnetic field by sunerposlng upon said fieldrhythmlcally'pulsm adapted to produce a selected partial to be used as acomponent or the desired tone; a source of current; pulsation-producingmeans in circuit with said source; a magnet associated with each of saidsounders; connections between said pulsation-producing means and saidmagnets for passing a unidirectional pulsated current through tin coilsof said magnets 01 a periodicity determined by the associatedpulsation-producing means; means for simultaneously passing a continuousunpulsated current tlfrough said magnets during the speaking of theirassociated sounders; relays in circuit with said magnets; means forpassing both the pulsated and unpulsated currents through said relays;means in circuit with said relays for selecting and mixing the partialsto be sounded as the desired composite tone; and expression-controlmeans in circuit with said partial-mixing system.

8. In an electromagnetically operated musical instrument, a series oisounders each adapted to ponent of the desired tone; a magnet associatedwith each of said sounders; a source of current; means for passing apulsatorycurrent through said magnets; and means for simultaneouslypassing an unpulsated current through said magnets, said means includinga resistance incircuit with each or said magnets and a condenser inshunt with each of said resistances.

9. In an electromagnetically operated musical instrument, a source ofcurrent; a series of sounders each adapted to produce a selected partialto be used as a component of the desired tone; magnets associated withsaid sounders; means for passing a pulsatory current through the coils0! said magnets; and means for simultaneously passing an unpulsatedcurrent through the coils of said magnets, said means including aresistance in circuit witli each of said magnets and condensers placedrespectively across the break and across the coil of each of saidmagnets.

10. In an electromagnetically operated musical instrument, a source ofcurrent; a series of sounders each adapted to produce a selected partialto be used as a component 01! the desired tone; magnets associated withsaid sounders, each 01 said magnets carrying two coils; means forpassing a pulsatory current through one coil of said magnets; means forsimultaneously passing an unpulsated current through the other of saidcoils: and condensers across the poles of one coil 01 said magnets.

11. In an electromagnetically operated musical instrument, a source orcurrent; a series of sounders each adapted to produce a selected partialto be used as a component of the desired tone; magnets associated withsaid sounders, each 0! said magnets provided with a permanentlymagnetized core; means -ifor passing a pulsatory current through thecoils of said magnets; and means for maintaining the magnetism oi. thecores of said magnets.

12. In an electromagnetically operated musical instrument employingmagnets for operating the sounders of said instrument; means formaintaining the magnetism of the cores 0! said magnets, comprising aswitch, magnets in circuit with said switch, contacts in circuit withsaid magnets,and means for opening and closing said contacts; a

' ity to each vibrating body, the vair -gap betweenthe cores of saidmagnets andthe vibrating bodies 'being very slight and the magneticcircuits short. 14. In anelectromagnetic ally operated musicalinstrument,- a speaking unit comprising a 'vibrating body; a resonatorassociatedwith said body;

a movable member supported by said vibrating body; a magnet coreassociated with said vibrating body, the air gap'between said core andthe vibrating body being slight; a choke coil carried by said resonator;a damper controlled by said coil; and means for opening and closing thecircuit of said coil.

15. In an electrically operated musical instrument, a speaking unitcomprising a vibrating body; a resonator associated with said vibratingbody; a movable member in proximity to said vibrating body; a magnetassociated with said body, the air-gap between the core oi sai magnetand the vibrating body being slight; d means for damping the tonesproduced by said'speaking- .unit, comprising a relay magnet, a secondmagnet in circuit with said relay magnet, a source of current in circuitwith said second magnet, a damper controlled by said magnets, and meansfor opening and closing the circuits of said magnets.

16. In an electromagneticaily operated musical instrument, a source ofcurrent; a series of sounders each adapted to produce a selectedpartial'to be used as a component of the desired tone; magnetsassociated with said sounders; and means for simultaneously passing aunidirectional and a pulsated current through said magnets.

- MELVIN L. SEVERY.

